Characterization of Liquid-Metal Fast Breeder Reactor Engineering Mechanics Effort by Lines-of-Assurance

One can classify development work by the Engineering Mechanics Program along physical lines by starting from the breeder reactor core and proceeding outward to the secondary containment. Another way to characterize the engineering mechanics effort is by the line-of-assurance (LOA) approach. The LOA approach was developed to provide quantifiable protection to the public against severe accidents. Accident prevention and mitigation was organized into the following four LOAs:

LOA-1:	Provides design features that render components and systems very reliable under operating conditions, reducing accident probability to very low level.
LOA-2:	Terminates accident with limited core damage if events go beyond LOA-1.
LOA-3:	Controls radioactive release if whole core disruption follows LOA-2.
LOA-4:	Controls and attenuates radiological consequences to the environment if containment is breached.

In the past, engineering mechanics effort was intense in the LOA-3 domain. More recently there has been a shift to LOA-1 for component and system reliability and to LOA-2 for the development of methodology reflecting minor core damage. Currently, the LOA-2 and LOA-3 domains are served by well-known engineering mechanics codes such as: REXCO, ICECO, ALICE, ICEPEL, STRAW, SADCAT, REX CAT, DYNAPCON, NEPTUNE, and SHAPS, developed in this program.